Midterm 2 Flashcards
What happened to the nasal opening in whales?
Moved to top of skull for blowhole
Two major kinds of whales?
toothed whales and baleen whales
Which is the largest of the baleen and toothed whales
blue whale and sperm whale
What is the fusiform shape?
streamlined body plan used in the water
What is the fluke
end of the tail common to cetaceans
Why do cetaceans have such thick dense bones despite being in the water?
Because they also have a thick layer of blubber, which floats, so they need heavy bones to sink and maintain neutral buoyancy
Why is there blood vessels that go into the blubber?
needs to innervate with blubber to provide a route for blood to reach edge of body and cool off - challenging to lose heat when you are large volume with small surface area
What is countercurrent exchange?
heat conservation mechanism found in flippers in aquatic mammals
- veins and arteries are paired, so arterial blood will warm venous blood, and venous blood will cool arterial blood
- loses heat but not to the environment
How do the deep diving mammals dive so deep?
Oxygenate entire blood stream and then exhale to prevent hyperinflated lungs
- flexible ribcage can collapse in on itself, helps regulate pressures
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What was enaliarctos?
early sea lion form, had weird toes
What are sirenians
super low metabolic rates
- fully aquatic
- somewhat related to elephants and hippos
- need warm water
- usually graze in shallow waters
Examples of convergent evolution in sirenians with whales and other species
- hairless fusiform shapes, no external ears, no hind limbs
- flattened tail, blubber
- bones very dense to overcome buoyancy
- lungs are long thin dorsal in abdominal cavity
- like elephants, cheek teeth are replaced horizontally
Are bats fully blind?
no they are effectively using their eyes to see sound
What is the most primitive of the two oldest monospecific genera of bats?
Onychonycteris finneyi
- fully flying bat from the Eocene
What was the oldest bat material found?
Icaronycteris index - found in Eocene beds
- insectivorous
- late eocene and oligocene have evidence for severa; Microchiroptera families
- megachiroptera famillies appeared in oligocene
Key differences between microchiropterans and megachiroptera (altho not always applicable / not a proper phylogenetic classification)
Microchiropterans
- echolocation
- insectivorous
- well developed tragus
- nose and facial ornamentation
- no claw on second digit
- tail and uropatagium present
- small body small eyes
Megachiropterans
- no echolocation
- frugivorous or insectivorous
- no tragus
- no special facial features
- claw on second digit
- tail and uropatagium absent
- large body size and large eyes
common traits of frugivorous mammals?
color vision to see fruit ripeness
grasping hands of some degree
- binocular vision
What is planetetherium?
late paleocene gliding mammal - similar to todays flying lemurs
What is rodentia?
order with the most species containing 2500 species
- highly specialized mastication with elongated curved continuously growing incisors
- diprotodont condition
- has evolved in lagomorphs, the extinct multituberculates, hyraxes, marsupials and primates (the aye aye)
What was protrogomorph?
primative condition with the masseter attachments to the skull limited to the zygomatic arch - paleocene rodents, mountain beaver
what is hystricomorph?
middle masseter unspecialized, deep masseter passes thru infra orbital foramen to attach anterior to the eye
- porcupine
What is sciuromorph
deep masseter is unspecialized, middle masseter is attached anterior to the eye
- squirrels
what is myomorph
midle masseter is attached anterior to the eye as in sciuromorph and the deep masseter passes up into the orbital area and through the infra orbital foramen - mouse
What was ceratogaulus?
horned gophers from this genus, only knonwn genus with horns and is smallest known horned mammal
late Miocene to early Pleistocene
What is the only eusocial mammal?
naked mole rats - have a caste system and a queen
What did capybaras used to look like and why?
south America was an island after the breakup of Pangaea, very few eutherian mammals on the island
- capybara like mammals filled the role of a large herbivore - unusual for a rodent
- no other large herbivores in SA
why did ungulate style running evolve multiple times
good for running away on toes , allows to maintain fast speeds, predators cant be ungulates due to ususally needing claws
What was desmostylus
probably a common ancestor to the proboscids and sirenians in the late miocene - looked like a hippo
- probably closer to manatee than elephant
What is weird about elephant teeth?
horizontal tooth replacement
What is the deal with elephant testicles?
not descended - internal
- similar to many afrotherian mammals
- might be a vestige of previous semiaquatic / aquatic life
- kidneys sort of say the same thing
surface area to volume ratio diminishing returns makes sense to be big
yes
Mammoth steppe grasslands?
v important habitat for Pleistocene megafauna , loss of habitat could be major reason for decline in mammoths and other species
